In the past, lubrication systems utilizing various lubricant storage and releasing materials were well known in the art and commercially acceptable for use in lubricating various apparatus, such as electric motors for instance. The past known lubrication systems utilized commercially available lubricant storage and releasing materials which were composed of various fibrous materials, such as cellulose and synthetic fibers, including wood fibers, cotton fibers, nylon fibers, rayon fibers and the like. One form of past lubricant storage and releasing material, such as an oil impregnated, fibrous wicking material, is commercially available for a lubrication system under the trademark "PERMAWICK" from the Permawick Company of Detroit, Mich. U.S. Pat. No. 2,966,459, issued Dec. 27, 1960, to M. L. Able for "Material Having Oil Retaining Properties" describes a lubricant storage and releasing material for a lubrication system composed of cellulose fibers and a lubricating oil. The cellulose fibers, which form the oil absorbing part of the wicking material, are made from wood fibers and a mixture of paper-containing fibers of wood, cotton and the like. U.S. Pat. No. 3,214,375, issued Oct. 26, 1965 to B. Berkeley for "Lubricated Wicking Material" discloses an oil impregnated storage and releasing material for a lubrication system composed of a blend of cellulose and synthetic fibers, such as nylon or rayon fibers. The cellulose fibers are described as being coated, at least in part, with a coating of polyvinyl alcohol. U.S. Pat. No. 3,466,244, issued Sept. 9, 1969 to M. L. Abel for "Oil-Impregnated Wicking Material" describes a lubricant storage and releasing material for a lubrication system of oil impregnated cotton linter fibers. Each of the above three patents is assigned to the Permawick Company, and these patents describe commercially available Permawick extrudable lubricant storage and releasing material for a lubrication system which in each instance has a distinctly fibrous structure. It is believed that at least one of the disadvantageous features of these past lubrication systems was that they only had a capacity for releasing a minor portion of the liquid lubricant thereof.
U.S. Pat. No. 2,960,371, issued Nov. 15, 1960, to L. E. Staak for "Bearing Lubricating Structure" and U.S. Pat. No. 2,979,779, issued Apr. 18, 1961 to L. E. Staak for "Improved Method of Providing a Bearing Lubricating Structure" both describe a lubrication system which comprises an oil impregnated lubricating structure formed by foaming an epoxy or phenolic material in place directly in a bearing housing thereby to form a unitary cellular foam structure in the bearing housing. After the foam is formed in place in the bearing housing, the foam is impregnated with an appropriate lubricating oil.
The use of fibers of glass, asbestos, and the like as fillers in a lubrication system is also known in the art. U.S. Pat. No. 2,303,068, issued Nov. 24, 1942 to G. H. Schoembaum for "Lubricant And Preparation Thereof" describes the use of asbestos fibers as a filler to form a viscous lubricating composition. U.S. Pat. No. 3,113,105, issued Dec. 3, 1963 to G. Slayter et al. describes a lubrication system utilizing silicone fluid lubricant incorporating short lengths of fibrous glass for use at high temperatures.
Various past lubricating systems for bearing structures of apparatus have employed felt feeder wicks. See, for example, U.S. Pat. No. 3,434,765, issued Mar. 25, 1969 to M. L. Abel for "Lubricating Bearing Assembly and Method of Marking Same", and U.S. Pat. No. 3,184,272, issued May 18, 1965 to A. J. Ridgway for "Lubricating Means for a Rotatable Device." In this type of lubrication system, it is desirable that the lubricant impregnated or storage and releasing material release the lubricating oil which it contains at a rate and in an amount sufficient to maintain a steady flow of lubricant through the felt wick to the rotating structure to be lubricated. It is believed that significant problem confronting the art with respect to the past lubrication systems resided in the disadvantageous feature that many of the lubricant compositions or extrudable lubricant storing and releasing materials, while capable of being extruded or otherwise packed into the bearing structure, were capable of releasing only a relatively small or minor portion of the total amount of lubricating oil contained therein. The smaller the releasable proportion of the liquid lubricant or oil, the shorter the life of the lubrication system, and hence of the bearing structure itself. Furthermore, the unreleased portion of the lubricant obviously was not available to perform the intended lubricating function.